为什么具有相同物理尺寸和分辨率的设备可能具有不同的密度？

Question

我正在测试华为MediaPad T5和三星Galaxy Tab A.他们有相同的财政规模（10.1英寸）和像素数（1920 * 1200），

问题1：为什么他们的密度不同（2.0和1.5）？密度仅仅取决于财政规模和像素数，对吧？

问题2：我使用dp为侧边栏（150dp）提供了相同的宽度，为什么它们看起来不一样？

    <android.support.v7.widget.RecyclerView
        android:id="@+id/fcom_categories"
        android:layout_width="150dp"
        android:layout_height="match_parent"
        android:background="@color/white"
        android:scrollbars="none"
        app:layoutManager="android.support.v7.widget.LinearLayoutManager"/>

huawei：

三星：

PS：我在那里打印显示规格

华为（xhdpi）

2019-03-31 17:37:23.801 15550-15550/com.ristoo I/DisplaySpecifications: displayName  = 内置屏幕
2019-03-31 17:38:05.072 15550-15550/com.ristoo I/DisplaySpecifications: width        = 1920
2019-03-31 17:38:05.072 15550-15550/com.ristoo I/DisplaySpecifications: height       = 1133
2019-03-31 17:38:05.073 15550-15550/com.ristoo I/DisplaySpecifications: widthPixels  = 1920
2019-03-31 17:38:05.073 15550-15550/com.ristoo I/DisplaySpecifications: heightPixels = 1133

2019-03-31 18:13:03.031 16436-16436/com.ristoo I/DisplaySpecifications: density   = 2.0
2019-03-31 17:38:05.073 15550-15550/com.ristoo I/DisplaySpecifications: densityDpi   = 320

2019-03-31 17:38:05.073 15550-15550/com.ristoo I/DisplaySpecifications: xdpi         = 225.777
2019-03-31 17:38:05.073 15550-15550/com.ristoo I/DisplaySpecifications: ydpi         = 225.777
2019-03-31 17:38:05.074 15550-15550/com.ristoo I/DisplaySpecifications: screenHeight = 1133
2019-03-31 17:38:05.074 15550-15550/com.ristoo I/DisplaySpecifications: screenWidth  = 1920
2019-03-31 17:38:05.074 15550-15550/com.ristoo I/DisplaySpecifications: orientation  = 2

三星（hdpi）

2019-03-31 17:40:57.310 24205-24205/com.ristoo I/DisplaySpecifications: displayName  = 内置屏幕
2019-03-31 17:40:57.311 24205-24205/com.ristoo I/DisplaySpecifications: width        = 1920
2019-03-31 17:40:57.311 24205-24205/com.ristoo I/DisplaySpecifications: height       = 1200
2019-03-31 17:40:57.312 24205-24205/com.ristoo I/DisplaySpecifications: widthPixels  = 1920
2019-03-31 17:40:57.312 24205-24205/com.ristoo I/DisplaySpecifications: heightPixels = 1200

2019-03-31 18:12:15.386 25654-25654/com.ristoo I/DisplaySpecifications: density   = 1.5
2019-03-31 17:40:57.312 24205-24205/com.ristoo I/DisplaySpecifications: densityDpi   = 240

2019-03-31 17:40:57.313 24205-24205/com.ristoo I/DisplaySpecifications: xdpi         = 225.777
2019-03-31 17:40:57.313 24205-24205/com.ristoo I/DisplaySpecifications: ydpi         = 225.77701
2019-03-31 17:40:57.314 24205-24205/com.ristoo I/DisplaySpecifications: screenHeight = 1200
2019-03-31 17:40:57.314 24205-24205/com.ristoo I/DisplaySpecifications: screenWidth  = 1920
2019-03-31 17:40:57.314 24205-24205/com.ristoo I/DisplaySpecifications: orientation  = 2

Answer 1

由制造商选择的像素密度桶。例如，在电视或平板电脑等设计用于远离脸部的东西时，它们可能会选择较低的密度，因此物品看起来更大。

因此，尽管150dp的项目在所有设备上的大小都相同，但仍会有一些变化。